/*
 * Copyright (C) 2011 ritwik.net
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.quhaodian.server;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.nio.ByteBuffer;
import java.nio.charset.Charset;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class JsonRpcServletTransport implements JsonRpcServerTransport {
  
  private static final int BUFF_LENGTH = 1024;
  
  private final HttpServletRequest req;
  private final HttpServletResponse resp;
  
  
  public JsonRpcServletTransport(HttpServletRequest req, HttpServletResponse resp) {
    this.req = req;
    this.resp = resp;
  }
  
  public String readRequest() throws Exception {
    InputStream in = null;
    try {
      String body = "";
      in = req.getInputStream();
      ByteBuffer byteData = readToByteBuffer(in);
      body = Charset.forName("UTF-8").decode(byteData).toString();
      
      return body;
    } finally {
      if (in != null) {
        in.close();
      }
    }
  }
  
  private static final int bufferSize = 0x20000; // ~130K.
  
  public static ByteBuffer readToByteBuffer(InputStream inStream)
      throws IOException {
    byte[] buffer = new byte[bufferSize];
    ByteArrayOutputStream outStream = new ByteArrayOutputStream(bufferSize);
    int read;
    while (true) {
      read = inStream.read(buffer);
      if (read == -1) {
        break;
      }
      outStream.write(buffer, 0, read);
    }
    ByteBuffer byteData = ByteBuffer.wrap(outStream.toByteArray());
    return byteData;
  }
  
  public void writeResponse(String responseData) throws Exception {
    resp.setCharacterEncoding("UTF-8");
    byte[] data = responseData.getBytes(resp.getCharacterEncoding());
    resp.addHeader("Content-Type", "application/json");
    resp.setHeader("Content-Length", Integer.toString(data.length));
    
    PrintWriter out = null;
    try {
      out = resp.getWriter();
      out.write(responseData);
      out.flush();
    } finally {
      if (out != null) {
        out.close();
      }
    }
  }
}
